Hybrid EPBM for mixed drive at Sleemanabad May 2011
Desiree Willis, Technical Writer, The Robbins Company
A hybrid EPBM machine from Robbins has launched on a drive of wide-ranging geology in India. The 10m diameter machine will face conditions that range from hard, massive marble to soft running gouge on its 12km long Sleemanabad Carrier Canal water transfer tunnel for contractors M/s Patel Engineering, SEW, and Coastal Projects Ltd (CPL).
10m Robbins Hybrid EPBM set for wide-ranging conditions

10m Robbins Hybrid EPBM set for wide-ranging conditions

The launch ceremony also marked the first time OFTA has been used for a hybrid EPBM. The Robbins-developed method allowed the TBM to be initially assembled on location, rather than in a manufacturing facility. Critical subsystems, such as the electrical and hydraulic systems, were tested before being shipped to the jobsite. After its Onsite First Time Assembly (OFTA), a commissioning ceremony last week celebrated the machine's launched on March 31.
The TBM is a fully functional hard rock single shield and soft ground EPBM built to bore in long sections of 180 MPa UCS jointed rock and marble, interspersed with clay and gravel. In sections of soft ground, the TBM runs as a standard, pressurized EPB system with an abrasion-resistant, shaft-type screw conveyor.
When short sections of rock or mixed ground are encountered, the machine can run in non-pressurized open mode. In longer sections of rock, the machine will converts to a hard rock single shield setup with the screw conveyor removed and replaced with a TBM belt conveyor.
The machine began excavation in full EPB mode, as the first 3km is expected to consist of mainly soft ground. After that initial section, the machine will be operated as a non-pressurized EPB or as a hard rock single shield depending on ground conditions.

First OFTA for a Robbins EPBM

Ole Pederson, the Robbins India Jobsite Manager, cited the remote project location and transport of parts as challenging aspects of the assembly and launch. Local support is easing these difficulties while providing an economic boost to the area. "The launch of this project has brought extra work to local farmers in the region, who are supporting operations at the jobsite. Parts delivery and food at the jobsite are also being provided by local businesses," said Pederson.
The Sleemanabad Carrier Canal is part of the larger Bargi Diversion Project for the Narmada Valley Development Authority, a division of the Madhya Pradesh Government. The major trans-valley canal will stretch 194km from the existing Bargi Dam on the Narmada River to arid areas.
Once complete, the Bargi Diversion Project will transfer 152m3 (40,000 gallons) of water per second to Katni, Satna, Panna, and Jabalpur districts, irrigating more than 100,000 hectares of land.
The Sleemanabad machine joins three other Robbins TBMs working on long irrigation-water supply projects in India. Two 10m rock machines are excavating the 43.5km AMR water supply tunnel and another for the 19.2km long Veligonda water transfer tunnel projects in Andhra Pradesh.

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